Many food products are fluids that have historically been thickened with starches. Some examples of foods in this group include gravies, sauces, stews, cream soups, pie fillings, puddings, and the like. A number of these products are intended to be served at high temperatures. A problem that exists in traditional starch thickened fluid foods is a loss of viscosity upon heating and holding at the high serving temperatures. This loss of viscosity upon heating poses problems for food manufacturers because viscosity is one of the most important sensory attributes of these food products The products must have a fairly high viscosity at serving temperatures in order to receive consumer acceptance.
Similar to starch thickened systems, foods thickened with food approved gums lose viscosity when heated to and held at elevated temperatures. Food products which are designed with gums to yield adequate viscosity at high temperatures suffer from several drawbacks. First, food products which exhibit adequate high-temperature viscosity generally exhibit undesirably high low-temperature viscosities. Secondly, such food products generally exhibit undesirable sensory characteristics such as gumminess, thickness, and ropiness.
Attempts have been made to try to obtain a starch based thickening composition which would impart the desirable viscosity properties to food products at elevated serving temperatures. U.S Pat. No. 4,597,974 discloses a mixture of rice starch and carob-bean flour as the components of a food product thickener, the reference does not disclose the use of any cellulose derivatives.
U.S. Pat. Nos. 3,969,340 and 3,970,767 disclose certain blends of starch and amylose starches which have been hydroxypropylated and inhibited to a specific degree in order to impart specific viscosity properties to the starches. The blends are disclosed as being able to impart thickening properties to food products prepared under retort conditions.
In order to overcome the deficiency of starch thickened systems, manufacturers have found it necessary to add high levels of starch to the food products. This causes the problem of excessive viscosity at the low temperatures at which many of the food products are processed and packaged. Food manufacturers and the consumer would both benefit from food products that exhibit less of a viscosity loss or even a viscosity increase on heating. Manufacturers could gain processing efficiencies and consumers could have access to foods which show a stable viscosity response to serving temperatures.